At least 23 people shot at a Toronto late night street party

(Scroll down for video) A festive block party suddenly turned into a war zone.

Two people died and 21 others injured in what could have been a gang-related shooting in a Toronto street party at night, raising fears of retaliatory violence in Canada's largest city.

In the second high-profile shooting in Toronto in less than two months, a 14 year old and a man, 23 years old, were killed. Police said another child was grazed by a bullet and is expected to recover, while another victim was in critical condition.

"We are very concerned not only with the quick resolution and the resolution of this crime, but the potential for retaliatory violence," said Toronto Police Chief Bill Blair at a press conference in which he pledged to step up the presence of police in response to this latest attack.

He said there was a "clear indication" of gang involvement in the incident. Two people exchanged gunfire at the party, where police had responded to complaints of noise. One of the injured has been arrested as a "person of interest".

The shooting took place in the suburb of Scarborough, about 20 kilometers or 15 miles east of the city center.

They raised fears about gun violence in a city that prides itself on its relatively low crime rate compared to the U.S. urban centers. Canada has strict laws controlling the use of firearms, and violent crime appears to be rare.

However, recently, two people were killed and six wounded in a gang-related shooting in downtown Eaton Centre, one of the most important tourist destinations of Toronto.

A witness told local news media that the latest incident took place at an annual barbecue party that had been scheduled for Sunday and then moved to Monday after the weekend storms. Police said hundreds of people were at the party when the shooting occurred.

"I am shocked and disgusted by this act of senseless violence," said Toronto Mayor Rob Ford in a statement.